Kavalactones are the primary active compounds found in the root of the Piper methysticum plant, commonly known as kava. Kava has a long history of traditional use in the South Pacific for its calming and anxiolytic (anxiety-reducing) effects. In recent decades, several clinical studies have evaluated the efficacy of kavalactones in the treatment of anxiety disorders. A number of randomized controlled trials (RCTs) and meta-analyses suggest that standardized kava extracts, containing known amounts of kavalactones, can reduce symptoms of mild to moderate anxiety, performing significantly better than placebo and in some cases comparably to low-dose benzodiazepines. For example, a 2003 Cochrane review and subsequent analyses have concluded that kava appears to be more effective than placebo in the short-term management of anxiety, though the effect size is typically moderate.

However, concerns about rare but serious hepatotoxicity (liver toxicity) have limited its widespread acceptance and use, leading to regulatory restrictions in several countries. The overall quality of evidence is limited by small sample sizes, variable quality of the studies, and heterogeneity in kava preparations and dosages. While there is scientific support for the anxiolytic effects of kavalactones, especially in the short term, more rigorous long-term studies are needed to fully establish both efficacy and safety.